Radiation-Induced Nucleation of Diamond from Amorphous Carbon: Effect of Hydrogen
YQ Sun and AG Kvashnin and PB Sorokin and BI Yakobson and WE Billups, JOURNAL OF PHYSICAL CHEMISTRY LETTERS, 5, 1924-1928 (2014).
Electron irradiation of anthracite functionalized by dodecyl groups leads to recrystallization of the carbon network into diamonds. The diamonds range in size from similar to 2 to similar to 10 nm and exhibit 111 spacing of 2.1 angstrom. A bulk process consistent with bias- enhanced nucleation is proposed in which the dodecyl group provides hydrogen during electron irradiation. Recrystallization into diamond occurs in the hydrogenated graphitic subsurface layers. Unfunctionalized anthracite could not be converted into diamond during electron irradiation. The dependence of the phase transition pressure on cluster size was estimated, and it was found that diamond particles with a radius up to 20 nm could be formed.
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